Fjölrit RALA - 15.08.1980, Side 21

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raents were performed. The internal organs were inspected, and samples
collected, especially if the lambs were found to be abnormal. Four
esophegal fistulated ewes were used for vegetation sample collection at
Hestur for chemical analysis and estimation of plantpreference. All
samples' were frozen as soon as possible.
The standing herbage was estimated at the livestock weighing time.
The method used was a double sampling method based on visual estimation
and some hand cutting and weighing to correct the estimates. Circular
frames to do the estimates were placed on the ground ca. 40-80 times in
each pasture. The standing herbage inside the frame was estimated and
the herbage inside every 5th to lOth frame cut, dried and weighed.
The standing herbage samples were used for chemical analysis and
in vitro digestibility measurements.
The same methods of chemical analysis were used as in previous years.
The samples were dried at 70-100*C. Crude protein was determined by auto
analyser method. The samples were dryashed and dissolved in acid for
mineral analysis. Phosphorus was measured by the formatiön of molybdate
vanadate complex. Calcium and magnesium were measured by atomic abosorbition
spectrophotometry. Sodium and potassium were measured by flamephotometry.
The method for measuring changes in the vegetation is based on fre-
quency sampling of the species and thus the change between years is shown
in percentage frequency. For this purpose two different sets of frames have
been used, one quadrat of 18 x 18 cm with another of 4 x 4 cm marked inside
one corner and a quadrat of .10 x 10 cm with another of 2 x 2 cm marked
inside. The size of the frame used is based on getting optimal frequency
of as many species as possible to measure the changes between the years.
The smaller quadrat (10 x 10/2 x 2 cm) was used on cultivated bog at Hestur
and on grassland rich in mosses at Alftaver where the vegetation is more
uniform. The bigger frame was used on uncultivated rangeland where the
vegetation is more variable. The most common species were identified in
the smaller frame and the less common in the big frame. The frames were
layed down at certain intervals along marked lines in every pasture. It was
tried to make the minimal number of 100 measurements in every two sets of
pastures, but for the bigger ones the number of measurements was much higher.
Although this method has proved to be very sensitive to changes in the
vegetation, it is inadequate for measuring botanical composition in the whole
pasture since the species are read in different quadrat sizes depending on
their frequency.